1. Field of the Invention
The invention relates to a control device for controlling current passing through a motor, more particularly to a control device for minimizing the presence of ripples in the current passing through the motor.
2. Description of the Related Art
A conventional control device for controlling current passing through a motor includes a pulse width modulator, a power module, and a current limiter for limiting the current passing through the motor. The current limiter includes a current detector provided to detect the current passing through the motor. When the detected current exceeds a predetermined value, an inhibit signal is produced by the current limiter and is sent to the power module to stop the supply of power to the motor. When the detected current drops below the predetermined value, the current limiter dismisses the inhibit signal to the power module to once again permit the supply of power to the motor. However, the inhibit signal is associated with a hysteresis action, and is not synchronous with the pulse width modulated control pulses generated by the pulse width modulator. Therefore, due to the different performance characteristics of the motor, the inhibit signal cannot be reset in each of the pulse width modulated cycles, thereby resulting in a relatively large ripple current to the motor.